This application claims the benefit of Korean Application No. 2002-7957, filed Feb. 14, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a hard disk drive, and more particularly, to a hard disk drive which can reduce vibration of a disk.
2. Description of the Related Art
A hard disk drive (HDD) is an auxiliary memory device of a computer that reads out data from a magnetic disk or records data on the disk by using a magnetic head. Recently, a variety of research and development efforts have focused on realizing a high speed, high capacity, low vibration, and low noise hard disk drive.
FIG. 1 is a perspective view showing a conventional hard disk drive. FIG. 2 is a vertical sectional view of the hard disk drive of FIG. 1.
Referring to FIG. 1, a conventional hard disk drive includes a housing 10, a spindle motor 30 installed in the housing 10 to rotate a magnetic disk (a hard disk) 20, and an actuator 40 having a magnetic head for recording and reading out data on and from the disk 20. The following description relates to one magnetic disk 20, although two are shown in FIGS. 1 and 2.
The housing 10 is installed in a main body of a computer and includes a base plate 11 to support the spindle motor 30 and the actuator 40, and a cover plate 12 coupled to the base plate 11 to enclosing and protecting the disk 20. The housing 10 is typically manufactured of a stainless steel or aluminum material.
The disk 20 is a recording medium for recording data and may be a single disk or a plurality of disks capable of being rotated by the spindle motor 30. If a hard disk drive has a plurality of disks, they are installed to be separated a predetermined distance from each other.
Referring to FIG. 2, the spindle motor 30 is supported by a flange 31 fixedly installed on the base plate 11. Typically, an upper end portion of a shaft 32 of the spindle motor 30 is fixedly coupled to the cover plate 12 by a screw 36. A hub 33 is rotatably installed around the outer circumferential side of the shaft 32 by interposing a bearing 37 therebetween. The disk 20 is inserted around the outer circumferential side of the hub 33. When a plurality of disks are installed, a ring type spacer 34 for maintaining a distance between the disks 20 is installed at the outer circumferential side of the hub 33. A clamp 35 for preventing escape of the disk 20 is coupled to an upper end portion of the hub 33.
Historically, storage capacity of hard disk drives has gradually increased. The storage capacity of a hard disk drive is proportional to a surface recoding density which is determined by the multiplication of a linear recoding density expressed by BPI (bits per inch) and a track density expressed by TPI (tracks per inch). BPI is totally affected by the development of a magnetic recording technology while TPI is mainly dependent on the improvement of a mechanical dynamic characteristic.
Track Misregistration (TMR) is a malfunction generated when data is recorded or reproduced on or from a track of a disk and is an important factor that restricts TPI and is therefore related to the storage capacity of the hard disk drive. A direct source of TMR is vibration of a disk. Disk vibration can be attributed to three sources: non-repeatable runout (NRRO) due to a defective ball bearing of the spindle motor, disk rocking motion due to gyro-moment of a rotating disk, and disk fluttering.
To increase reliability of performance of a hard disk drive by reducing TMR, disk vibration generated during operation needs to be reduced. Accordingly, as shown in FIG. 3, it is a recent trend to decrease a gap between the disk 20 and each of a base plate 11xe2x80x2 and a cover plate 12xe2x80x2 by forming the surfaces of the plates 11xe2x80x2 and 12xe2x80x2 facing the disk 20 to protrude toward the disk 20. When the gap between the disk 20 and each of the plates 11xe2x80x2 and 12xe2x80x2 is sufficiently narrow, disk vibration is reduced by air compressed therebetween. But when the gap between the disk 20 and each of the plates 11xe2x80x2 and 12xe2x80x2 decreases, a relatively small external impact may cause, the disk 20 to collide against the base plate 11xe2x80x2 or the cover plate 12xe2x80x2, thereby damaging the disk 20. So while the damping effect by compressed air increases as the gap between the disk 20 and each of the plates 11xe2x80x2 and 12xe2x80x2 decreases, the disk 20 is more easily damaged. Thus, there is a limit in reducing the gap. Typically, the gap between the disk 20 and each of the plates 11xe2x80x2 and 12xe2x80x2 is about 1 millimeter, which provides a damping effect by compressed air. However, a sufficient disk vibration reducing effect cannot be obtained.
To solve the above-described problems, it is an aspect of the present invention to provide a hard disk drive in which air pumping grooves for pumping air toward the outer circumferential side of a disk to reduce vibration of the disk are provided in the base plate and the cover plate.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
To achieve the above and/or other aspects, there is provided a hard disk drive comprising a housing having a base plate and a cover plate, a spindle motor installed on the base plate, at least one data storage disk installed at the spindle motor, and an actuator, pivotably installed on the base plate and having a magnetic head recording and reading out data on and from the disk. At least one groove to pump air toward an outer circumferential side of the disk is formed in any one of the surfaces of the base plate and the cover plate which faces the disk. An outer end of the groove is located at a position inwardly separated a predetermined distance from an edge of the disk such that an air journal zone having a predetermined width is formed along a circumferential direction of the disk between the outer end of the groove and the edge of the disk. Vibration of the disk is thereby reduced by a damping operation of compressed air pumped by the groove having a high pressure in the air journal zone.
It is an aspect of the present invention that a protruding surface protruding to a predetermined height toward the disk is formed at at least one of an upper surface of the base plate and a lower surface of the cover plate to reduce a distance from the disk, and the groove is formed in the protruding surface.
It is an aspect of the present invention that the groove is formed in multiple numbers in a circumferential direction of the disk at a predetermined interval, and that the groove is extended in a radial direction from an inner circumferential side of the disk and curved in a direction in which the disk rotates.
It is an aspect of the present invention that a bottom surface of the groove is inclined toward the disk at an outer end portion of the groove.